Linear Patterns with variable spacing

David_Bower1

Making a linear pattern with unequal spacings is a common feature in cad but I can't find how to do it in Onshape. I can only find equal spacing. Can someone show me how to do unequal spaced patterns please? Do I create ab equal pattern and edit dimensions somehow?

S1mon

It really depends on what you’re patterning and how complex the “unequal spacing” is. Then there are issues around performance and ease of modification. An example (images, public models, etc) would help us guide you a lot. 

David_Bower1

Hi S1mon, All I want to do is pattern a line of hole features where the first and last spacing is different to the rest.

Evan_Reese

If I needed what you describe on a real project, I'd just manually model the end holes after the regular pattern. Here's an example of that.

BUT since i'm replying here for the fun of it I'll show some unintuitive, complex ones too, which could be valuable in certain cases (like modeling guitar fret spacing). They are all based on using a feature pattern on variable features so the variable values change each time the feature pattern loops over those features. I made the var

#i = 0

and then another one

#i = #i + 1

If I pattern the second #i feature, it will increase by 1 every time the features loop, and you can use the number to drive all kinds of things. You could multiply it by a length like I do in this part studio or you could use it to index an existing array of values like in this part studio.

In the first one, I'm also using some conditional logic to tell it how much the spacing should change each time. This is a ternary function. If you're not used to the syntax it's basically

[true/false statement] ? [result if true] : [result if false]

my true/false statement is

(#i = 0)||(#i = #holes - 1)

Which is asking "is #i is zero or the holes - 1". In other words, "is it the first or last hole?". If it is, then I use #endSpacing and if not I use #defaultSpacing

I'm sure I'm leaving things out here because I don't know your comfort level with code, but feel free to ask followups. As I said, it's not intuitive, but it is a fun puzzle.

NeilCooke

Yeah, I don't know of any CAD programs that let you do that easily (prove me wrong) and @Evan_Reese's solution is correct but somewhat over the top - I would probably make it out of 3 patterns: pattern for first and last, pattern for first and second, pattern for second to n.

S1mon

I normally avoid sketch patterns, but they might be a good choice for this situation, depending on how many holes we're talking about, and which dimensions you want to control.

David_Bower1

Other cad packages have the ability to do variable patterns where you can edit the dimensions between each instance after creating it, or even disable some instances. Sketch patterns could be a good solution. I don't really have time to play with code as fun as it sounds 

NeilCooke

David_Bower1 said:

Other cad packages have the ability to do variable patterns where you can edit the dimensions between each instance after creating it, or even disable some instances. 

I know you can disable instances in other CAD, but can you name which CAD can edit individual dimensions? (For my education - Table patterns don't count). Thanks!

David_Bower1

I am pretty sure it's possible in Creo and Catia to set variable spacing then edit the dimensions between each instance individually if it varies from the default you set.

Evan_Reese

I agree my "solutions" were over the top. I meant them to be examples of some of the powerful stuff you could set up in other situations. I do remember liking how Solidworks handled it. Here's a video showing the workflow https://youtu.be/oisuBea5LI8?t=113

NeilCooke

Evan_Reese said:

I agree my "solutions" were over the top. I meant them to be examples of some of the powerful stuff you could set up in other situations. I do remember liking how Solidworks handled it. Here's a video showing the workflow https://youtu.be/oisuBea5LI8?t=113

Huh, I didn't know you could do that - must be a recent-ish addition? My apologies for doubting you @David_Bower1

glen_dewsbury

Is there an IR for this we can jump on?

Evan_Reese

NeilCooke said:

Evan_Reese said:

I agree my "solutions" were over the top. I meant them to be examples of some of the powerful stuff you could set up in other situations. I do remember liking how Solidworks handled it. Here's a video showing the workflow https://youtu.be/oisuBea5LI8?t=113

Huh, I didn't know you could do that - must be a recent-ish addition? My apologies for doubting you @David_Bower1

If my memory serves me, I recall doing this before I even switched to Onshape over 6 years ago, but I don't remember if it's been this robust for that long or not.